The plus/minus basketball stat: Where it came from, and why experts vary on how useful and informative it is

Andy Hill has no trouble remembering, nearly a half-century later, when he first came to believe he might have conceived something worthwhile when he introduced the “Team Contribution Index” to college basketball.

Because it was John Wooden who said so.

A member of three UCLA championship teams from 1970 to 1972, Hill was coaching at Santa Monica Community College in 1976, and he was trying to get players to become as invested in victory as all his Bruins teammates had been. He decided one obstacle to this was that every statistical category in a box score – save for the assist – could be twisted by a player into self-aggrandizement. So he came up with something new.

“The underlying principle was: How do I get these guys to care, to pay attention to what I’m paying attention to, which is how is the team doing?” Hill told The Sporting News. “And I wrote this article, and I thought, before I send this into people, how would I know if this was something that lots of people were doing?

“So I went to see Coach. And I walked down there with this article. And I asked him to read it. And he looked and me, and he said, ‘Well, that’s a great idea!’”

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If John Wooden had not seen such a thing on the way to 10 NCAA championships, Hill knew he was onto something new. And if John Wooden liked it, well, that spoke for itself. Hill submitted his article to Scholastic Coach magazine, and it was printed in the January 1977 issue. His invention has lasted to this day, although you won’t find “Team Contribution Index” in any basketball box score.

Instead, what you will find on official NCAA, NBA and FIBA box scores is this: +/-

That’s right. TCI was Hill’s name for the plus-minus rating: How many points were scored for and against your team while you were active in the game?

The NHL has been doing this since the 1950s, but Southern California wasn’t exactly hockey country before Wayne Gretzky came along a few decades later. Hill knew nothing about the sport. And he acknowledges there may have been basketball coaches or teams that charted this concept individually, but there was no printed record of it until his article was published in Scholastic Coach magazine.

“It’s now ubiquitous in box scores, and I don’t know when that started,” Hill told TSN. “But this actually encourages team play. It gets people to think how the team is doing when I’m in the game, which is not natural for some people.

“Coach said he never talked about winning, and he didn’t. But what you do when you have people who don’t care about winning as much as you do? The truth is, you don’t have to talk to Bill Walton about winning. You don’t have to talk to Mike Warren about: Do you want to win? You know he does. That was part of what he recruited, part of the genius of his recruiting. He never talked about winning because he only had guys who were winners.”

The plus/minus statistic has experienced a curious history since being introduced by Hill. It was added to official NBA box scores starting in the 2007-08 season. In February 2009, it was cited prominently in an article by bestselling author Michael Lewis – yes, the guy who helped revolutionize baseball statistics with the publication of “Moneyball” – about Shane Battier’s successful tenure with the Houston Rockets. It was called, “The No-Stats All-Star”, and it was explained the only number that seemed to capture his value to the team was plus/minus, which was enthusiastically endorsed by analytics-centric GM Daryl Morey.

More than 15 years later, it’s still on the box scores, but in college hoops it seems to be used more often to verify a belief than to generate one.

Coach Greg Gard of Wisconsin told The Sporting News he does look at the numbers, “But it’s so reliant on what the others on the floor are doing with you…good or bad.”

Years ago, college basketball stat legend Ken Pomeroy published an article on his popular KenPom.com site in which he argues against the reliability of plus/minus.

“I used to have a little pinned tweet that said: Sports analytics should be like digging a grave. Six inches isn’t enough, but 600 feet is just overkill,” Erik Haslam of the college hoops website Haslametrics told TSN. “I think to a certain degree today, we’re probably at 150 feet and people are looking for a brand-new shovel.

“I just decided I didn’t want to go down to the player level with analysis. First of all, there’s so many situations where the player level can be misleading. The very same holds true with the plus/minus, but that can be said for any metric. I think what the plus/minus is – it’s evidence at a crime scene. It’s something you can use, and it’s a valuable tool, if used correctly. That’s not to say it can’t be misleading, or it can’t be gamed.

“I think it probably holds value. But you have to understand everybody’s going to criticize and construe it and find that one situation where it’s really a bad idea.”

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Statistician Bart Torvik, whose “T-Rank” website has become increasingly popular in part because it allows users to check efficiency stats for teams over particular segments of time, acknowledges the basic idea behind plus/minus is sound.

“It’s certainly an appealing idea – that what matters is the points that are scored when people are on the court, and this is the purest way to do it,” Torvik told TSN. “Hustle stats and shutting the guy down defensively – you can’t really quantify a lot of that stuff, but it should show up in the score somehow. I think that the issue is, especially in college, there’s just too much variation about what happens on the court and when they aren’t.

“There’s just not enough games, not enough time for that randomness to really work itself out. I think that’s the problem with it. It’s a great idea, but there’s just not enough information. And I think the other idea is: Who’s on the court with you? That can affect it, too.”

Harold Shelton III, senior manager of research at Big Ten Network, is much more enthusiastic about the value of plus/minus and perceives considerable value from it relative to both lineup combinations and individual contributions.

“For a one-game sample, I think it can be fluky or noisy and not as beneficial,” Shelton told TSN. “I think in a larger sample size it can tell you a story of a player who makes winning plays that might not show up on a stat sheet like a point, rebound or block would.”

What’s interesting is there have been statisticians who, in a sense, have taken plus/minus in a different direction, or possibly to a whole new level. The fascinating site CBBAnalytics.com has a tab called “on/off”, which breaks down the differential in a wide variety of stats when a specific player is on or off the floor. For instance, the offensive rating for Purdue — how many points scored per 100 possessions — increases by 28.2 when All-American Zach Edey is in the game. Kentucky’s offensive rating goes up by 13.3 with freshman guard Reed Sheppard on the floor.

It’s not the same concept as plus/minus, but it’s the same notion.

Andy Hill

(UCLA Athletics)

It’s a long way from the time when Hill first considered the possibility of a stat that could help convince his boss at Santa Monica that a 5-foot-3 guard named Katsumi “Kats” Chinen was helping to make their team better even though he was that size and not a particularly great shooter.

“You see a 5-3 guy, everybody wants to post him up. Guess what? This guy was stronger than heck. He was better defending the post than they were at playing the post,” Hill said. “And the guy I was coaching with, he couldn’t see it. How do I get him to understand? We’ve got to play this kid more. We’re winning when he’s on the floor.

“Honestly, like an idiot, this incandescent light bulb – there were no LEDs in those days – goes off in my head: Well, it’s all up on the scoreboard. That’s the value. And because I didn’t know any better, I wrote an article and tried to share the idea.

“That’s where it came from: trying to talk my guy into playing the kid more, and really relating to the idea of getting players who might not be committed to the idea that the team winning was more important than them doing well. Which, at this point in my life, I can understand that. You know, if you’ve never been a part of a great team, you don’t really understand the value of it.”

In a way, the plus/minus rating began the process of restoring Hill’s relationship with Wooden, which was strained after he’d spent three years playing for the Wizard of Westwood without generating even a couple months’ worth of playing time. He scored 144 career points in 69 games. He got in for a single minute in the first of his three championship games.

Not long afterward, a meeting with Gary Cunningham, a Wooden assistant during Hill’s playing days who eventually wound up among the coach’s successors, convinced Hill there might be less wrenching uses of his UCLA education. Cunningham eventually left coaching to become an athletic director. Hill joined the entertainment business and worked his way up to president at CBS Productions.

Along the way, he made the conscious decision to reconnect with Wooden, and Hill wound up writing a bestselling book about what he’d learned from playing (or not) at UCLA. That book helped him launch a side enterprise as a motivational speaker.

“I thought I didn’t really get much of a chance,” Hill said. “One of the big moments in my relationship, Coach told me a story in his little den about being in the 10th grade, and he wasn’t starting. And he was so mad, because he was convinced he should be starting. He stripped down to his jock strap and tennis shoes, threw all of his stuff on the floor and stormed out of the gym.

“Now, I had swallowed whole the legend of John Wooden, the great player of Indiana, and I said, ‘You didn’t start? And it pissed you off?’ In that moment, what I understood was John Wooden didn’t ignore me and my pain because he didn’t understand. John Wooden ignored me and my pain because he got it, and he couldn’t take it. Which is very human. And I said to him, ‘God, I wish you’d told me this.’

“It was really powerful. He just said, ‘I’m sorry.’ For me, I can handle that. I can deal with that.”

Turns out there were pluses and minuses to being coached by Wooden. But mostly pluses.

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